There are many signal transduction systems in cells which are functionally linked to each other to control the proliferation, growth, metastasis and apoptosis of cells (William G. Kaelin Jr., Nature Reviews Cancer 5, 689, 2005). The breakdown of the intracellular controlling system by genetic and environmental factors causes abnormal amplification or destruction of the signal transduction system leading to tumor cell generation (Douglas Hanahan and Robert A. Weinberg, Cell 100, 57, 2000).
Protein tyrosine kinases play important roles in such cellular regulation (Irena Melnikova and James Golden, Nature Reviews Drug Discovery 3, 993, 2004), and their abnormal expression or mutation has been observed in cancer cells or autoimmune diseases. The protein tyrosine kinase is an enzyme which catalyzes the transportation of phosphate groups from ATP to tyrosines located on protein substrates. Many growth factor receptor proteins function as tyrosine kinases to transport cellular signals. The interaction between growth factors and their receptors normally controls the cellular growth, but abnormal signal transduction caused by the mutation or overexpression of any of the receptors often induces various cancers or autoimmune diseases such as rheumatoid arthritis.
With regard to the roles of these tyrosine kinases, a variety growth factors and receptors thereof have been investigated, and among them, epidermal growth factors (EGF) and EGF receptor (EGFR) tyrosine kinases have been intensely studied (Nancy E. Hynes and Heidi A. Lane, Nature Reviews Cancer 5, 341, 2005). An EGFR tyrosine kinase is composed of a receptor and tyrosine kinase, and delivers extracellular signals to cell nucleus through the cellular membrane. Various EGFR tyrosine kinases are classified based on their structural differences into four subtypes, i.e., EGFR (Erb-B1), Erb-B2, Erb-B3 and Erb-B4, and it is known that EGFR activating mutations, such as L858R point mutation in exon 21 and in-frame deletions in exon 19 of the EGFR tyrosine kinase domain, are the important cause of non-small cell lung cancer.
Gefitinib (AstraZeneca) was initially developed as a small molecule for the inhibition of EGFR tyrosine kinases, which selectively and reversibly inhibits EGFR (Erb-B1). Erlotinib (Roche) has also similar characteristics. These EGFR-targeted drugs are efficacious for non-small cell lung cancer (NSCLC) and provide therapeutic convenience for patients with EGFR activating mutations.
However, it has been reported that the development of resistance lowers the activity of a particular drug used in EGFR-targeted therapies. It has been already reported that about half of the patients administered with Gefitinib or Erlotinib exhibited the resistance to the drugs due to the induction of the secondary EGFR T790M mutation (William Pao et al., Public Library of Science Medicine, 2(3), 225, 2005, Cancer Res, 67(24), 11924, 2007). Further, it has been recently found that irreversible inhibitors to target for EGFR are more beneficial in securing excellent efficacy and overcoming the resistance development, as compared to the conventional reversible inhibitors such as Gefitinib and Erlotinib (Danan Li et al., Cancer Cell 12, 81, 2007; and Anja Michalczyk et al., Bioorganic & Medicinal Chemistry 16, 3482, 2008). Hence, irreversible inhibitors such as BIBW-2992 (Afatinib, Boeringer Ingelheim) (C H Mom et al., British Journal of Cancer 98, 80, 2007), PF00299804 (Dacomitinib, Pfizer) (Engelman J A, et al., Cancer Res. 67, 11924, 2007), and AV-412 (AVEO Pharmaceuticals) (Tsuyoshi Suzuki et al., Cancer Sci. 98(12), 1977, 2007) have been developed and are currently in the clinical stage. The compounds have been known to form a covalent bond with Cystein773 (Cys773) positioned at an ATP domain of EGFR, thereby irreversibly blocking the autophosphorylation of EGFR and thus efficiently inhibiting the signal transduction of cancer cells (David W. Fry et al., Proc. Natl. Acad. Sci. U.S.A. 95, 12022, 1998), and exhibit higher inhibitory activities compared to the reversible inhibitors commercially available as dual inhibitors of EGFR/HER-2, or pan-HER inhibitors in in vitro activities and in various in vivo models of carcinomas (Jeff B. Smaill et al., J. Med. Chem. 42, 1803, 1999). However, the compounds may cause serious side effects such as skin rashes, diarrhea and weight loss due to high activities to EGFR WT (wild type) present in normal cells, when they are administered in a dose sufficient to overcome the resistance induced by EGFR T790M mutations, and this has been limited their clinical application, (Martin L. Sos, et al., Cancer Res. 70, 868, 2010).
As evidenced by clinical tests of the irreversible inhibitors in non-small cell lung cancer, the compounds have exhibited improved activities but still weak therapeutic effects in the resistance development of cancer patients, compared to the conventional reversible inhibitors. Accordingly, there has been a continued need to develop a novel drug that is effective in drug-resistant cancers and has no adverse side effects.
Meanwhile, there are various evidences that B-cells (B-lymphocytes) and T-cells (T-lymphocytes) play a key role in the pathogenesis of inflammatory diseases, autoimmune diseases and/or immunity mediated diseases.
For instance, aberrant signaling can induce deregulated B-cell proliferation and differentiation to cause all sorts of lymphoma including various acute or chronic lymphoid leukemia and can cause formation of autoantibodies that lead to multiple inflammatory diseases, autoimmune diseases and/or immunity mediated diseases.
Bruton's tyrosine kinase (BTK) is a member of the TEC family of tyrosine kinases, and plays an important role in B-cell activation and signal transduction. BTK plays an essential role in B-cell signaling pathway which links the B-cell receptor (BCR) stimuli on the surface of B-cells to the response in downstream cells. Further, BTK has been known to be a critical regulator of B-cell development and mature B-cell activation and survival (Khan et al., Immunity 3, 283, 1995; Ellmeier et al., J. Exp. Med. 192,1611, 2000; Kurosaki, Current Opinion in Immunology 12, 276, 2000; Schaeffer and Schwartzberg, Current Opinion in Immunology 12, 282, 2000). Thus, inhibition of BTK could be a therapeutic approach to block B-cell mediated disease processes.
For example, it has been known that BTK-deficient mice are resistant to collagen-induced arthritis and BTK inhibitors have been demonstrated dose-dependent efficacies in a mouse model of arthritis (Jansson and Holmdahl, Clin. Exp. Immunol. 94, 459, 1993; Pan et al., Chem. Med. Chem. 2, 58, 2007). Thus, effective BTK inhibitors may be useful in the treatment of rheumatoid arthritis.
In addition, BTK is also expressed by cells other than B-cells that may be involved in disease processes, i.e., bone marrow-derived mast cells. It has been reported that the antigen-induced degranulation is suppressed in BTK-deficient bone marrow-derived mast cells (Iwaki et al., J. Biol. Chem. 280, 40261, 2005). This shows that BTK could be useful to treat pathological mast cell responses such as allergy and asthma.
Also, monocytes, in which BTK activity is absent, showed decreased TNF-α production following stimulation (Horwood et al. J Exp Med. 197, 1603, 2003). Therefore, TNF-α mediated inflammation could be modulated by BTK inhibitors.
Furthermore, BTK has been reported to play a role in apoptosis as some of regulators (Islam and Smith, Immunol. Rev. 178, 49, 2000). Thus, BTK inhibitors would be useful for the treatment of certain B-cell lymphomas and leukemias (Feldhahn et al., J. Exp. Med. 201, 1837, 2005).
Meanwhile, T-cells play a role in transmitting signals delivered through the T-cell receptor (TCR) on the cell surface from antigen presenting cells into downstream effectors by the activation of intercellular various kinases such as janus kinases. At this time, they secrete various interleukin (IL) or interferon-γ to activate various leukocytes as well as the B-cells. Protein kinases involved in signal transduction in T-cells are Janus kinases (JAK) such as JAK1, JAK2, JAK3 and TYK2, IL-2 inducible T-cell kinases (ITK), and TEC family of kinases such as resting lymphocyte kinases (RLK).
Janus kinases involving JAK3 have been widely investigated as a target for autoimmune and/or inflammatory diseases. Among them, unlike JAK2 involved in hematosis and erythrocyte homeostasis or JAK1 expressed in various tissues, JAK3 is expressed in lymphocytes and plays a very important role in signal transduction via various cytokines, i.e., IL-2, IL-4, IL-7, IL-9 and IL-15, which is more attractive (Flanagan et al, Journal of medicinal Chemistry, 53, 8468, 2010). According to animal studies, JAK3 plays a role in the maturation of B-cells and T-cells as well as in maintaining T-cell functions.
Therefore, JAK3 inhibitors may be useful in the treatment of rheumatoid arthritis, psoriasis, atopic dermatitis, lupus, multiple sclerosis, Type I diabetes and complications from diabetes, cancer, asthma, autoimmune thyroid disorders, ulcerative colitis, Crohn's disease, Alzheimer's disease, leukemia, and other indications where immunosuppression would be desirable, such as organ transplants or xeno transplantation (Pesu M, Laurence A, Kishore N, et al., Immunol Rev 223, 132, 2008; Kawahara A, Minami Y, Miyazaki T, et al., Proc Natl Acad Sci USA 92, 8724, 1995; Nosaka T, van Deursen J M A, Tripp R A, et al., Science 270, 800, 1995; Papageorgiou Ac, Wikman L E K., et al., Trends Pharm Sci 25, 558, 2004).
Meanwhile, other TEC family of kinases also play an important role in T-cell activation (Pamela L. Schwartzberg, et al., Nature Reviews Immunology 5, 284, 2005). For example, deletion of ITK which is characteristically expressed in T-cells in mice led to decreased cell proliferation which is induced by stimulation via T-cell receptors and decreased secretion of various cytokines such as IL-2, IL-4, IL-5, IL-10 and IFN-γ (Schaeffer et al., Science 284, 638, 1999; Fowell et al., Immunity 11, 399, 1999; Schaffer et al., Nature Immunology 2, 1183, 2001).
In addition, in ITK-deficient mice, immune symptoms of allergic asthma were attenuated and lung inflammation, eosinophil infiltration, and mucous production in response to challenge with the allergen ovalbumin were drastically reduced (Muller et al., Journal of Immunology 170, 5056, 2003). This shows that ITK inhibitors would be useful in the treatment of asthma.
Further, ITK has also been implicated in atopic dermatitis. This gene has been reported to be more highly expressed in peripheral blood T-cells from patients with severe atopic dermatitis, compared with controls or patients with mild atopic dermatitis (Matsumoto et al., International archives of Allergy and Immunology 129, 327, 2002).
Meanwhile, RLK functions to activate the secretion of IL-2 which is produced by signal transduction of T-cell receptors of splenocytes. Thus, the inhibition of RLK may reduce various responses by T-cells (Schaeffer et al., Nature Immunology 2, 1183, 2001; Schaeffer et al., Science 284, 638, 1999).
In addition, bone marrow tyrosine kinase (BMX) has been known to be involved in epithelial and endothelial cell migration (Pan et al., Mol. Cell. Biol. 2002, 22, 7512). Therefore, BMK inhibitors may be developed as anticancer agents for inhibiting the metastasis of cancer cells and angiogenesis.
As above, since TEC family kinases such as BTK, ITK, RLK, BMX and others and Janus kinases such as JAK3 play a critical role in the activation of B-cells and/or T-cells which is implicated in the pathogenesis of inflammatory diseases, autoimmune diseases, and immunologically mediated diseases, a compound for effectively inhibiting the kinases may be useful as a therapeutic agent for various inflammatory diseases, autoimmune diseases, and immunity mediated diseases.
Furthermore, a compound for inhibiting BTK involved in B-cell activation inducing B-cell lymphoma, and BMX involved in metastasis of cancer cells may be useful as an anticancer or antitumor agent.
Therefore, the development of a compound, which can inhibit above kinases and selectively inhibit variant EGFRs such as secondary T790M mutations as well as L858R point mutation at exon 21 or in-frame deletion at exon 19, is one of very important challenges.
Even though it was suggested that EGFR irreversible inhibitors, which form a covalent bond with Cystein773 (Cys773) positioned at an ATP domain of EGFR, may show inhibitory effects on the activities of TEC family of kinases such as BTK, ITK, RLK and BMX in which cysteine is present in a same position of the amino acid sequence, as well as kinases such as JAK3 or BLK (Wooyoung Hur, et al., Bioorg. Med. Chem. Lett. 18, 5916, 2008), there has been no developed for a compound which can inhibit irreversibly, selectively and effectively variant EGFR, BTK, JAK3, ITK, RLK, BMX and/or BLK.